Now it seems that both of the victims in the video also had Kazakhstan connections. Zhanbolat Mamaev is apparently from Merke (also spelled Merki), in Zhambyl Oblast. Most of my time in Kazakhstan was in Taraz, the capital of Zhambyl Oblast. Although, to the best of my knowledge, I never went to Merki region or town. The other victim, identified as Sergei Ashimov, was apparently born in Karaganda, but later moved to Russia.

Anyway, this stuff probably doesn't matter much to you. But it makes the video somehow closer and even more chilling for me.

On the other hand, it totally makes sense for the FSB to use Kazakhs or agents with Central Asian connections if they want to infiltrate a group like the Islamic State.